How did I install Steam on K: on my computer then ? My whole C: partition is 230 GB and my Steam folder is about 182 GB... it would be crazy to install Steam on C: in the first place.

Surely it must be possible to install it on any drive. If not....

Copy the Steam folder into another partition...

Start the registry editor by typing regedit in Run/Search and pressing Ctrl+Shift+ Enter (to start it in elevated mode/admin rights). If you don't use Ctrl+Shift+Enter, you might find the keys read only and you may not be able to edit them.

Go to HKEY_CURRENT_USER\Software\Valve\Steam

Edit SteamExe and SteamPath to point to where steam.exe is on the new drive and where the Steam folder is (keep the / in the paths) ... also change the ModInstallPath and SourceInstallPath

Find Steam in the list, change it to the new path. The value is "K:\Steam\steam.exe" -silent on my computer. This will only be here if you've configured Steam to automatically start when you log in.

Restart the computer, and Steam should start from the new drive and run everything from the new drive. If you want to make sure, rename Steam in Program files to Steam2 and see if everything still runs. It will run.

If there's something wrong, revert the changes back to the original ones and reboot and everything will work as before.

You may be moving the files that Steam uses to run onto another drive, but Windows makes sense of the installation through the registry... where is the registry again?

But the main point is not to make sure that nothing gets written to C:. Rather, the point is that when programs make changes to the registry, it mucks up Windows. The effect is cumulative when lots of keys are being entered and changes made, and in general, I agree that Steam itself is not as bad, say, as Norton or AIM, but I do think it's an offender.

It seems that you have this stubborn idea in your head that steam is responsible for screwing Windows
Steam actually behaves quite well as far as the Registry is concerned. Esspecially compared to others, where M$ itself is its worst offender. Steam installs, writes stuff in registry and thats it, it doesn't rewrite in registry ever 5 minutes.

Yes, portable apps (eg ccleaner, and others) are a lot better; i would even argue that batch-files are even better; but it is what it is... and as i said, there are far worse offenders.

I would not worry toomuch about what steam does in the registry; what it does to (video)memorywith its overlay is far , far worse.

As for registry,... there are tools for cleaning/maintaining the registry.

As for steam, it has been pointed out that you can install it anywhere, preferably on another drive.

However, since you have SSD, this nifty little app "steam mover" allows you to put individual games onto your C: drive.
In most cases that is not needed, but there are a few games **cough**rage**cough** that benefit from launching off an SSD.